재활용품-신품 통합관리시스템의 최적운영에 관한 연구

Abstract

This paper studies a joint EOQ and EPQ model in which a stationary demand and three level dynamic lot sizing problem in which the dynamic demand can be satisfied by recycled products as well as newly purchased products. The model assumes that a fixed quantity of the used products are collected from customers and later recovered for reuse. The recovered products are regarded as perfectly new ones. We also assume that the number of orders for newly purchasing items and the number of recovery setups in a cycle can be mutually independent integers. Under these assumptions, chapter 3 develop an optimization model obtaining the economic order quantity for newly procured products, the optimal lot size for the recovery process, and the sequence of the orders and the setups, simultaneously. And then a simple solution procedure to find the optimal control parameters is proposed. To validate the model and the solution procedure, finally, some computational experiments are presented. Chapter 4 obtains ⅰ) the economic order quantity for newly procured products, ⅱ) the optimal lot size for the recovery process, and ⅲ) the purchasing price of the used items, simultaneously, using a genetic algorithm. Chapter 5 present a mixed integer programming model to obtain the economic recovery schedule for the recoverable items and production schedule for the row materials as well as the economic order schedule for newly procured products, simultaneously. Applying a commercial optimization software (e.g., LINGO or CPLEX) to this model, one can easily find optimal solutions for small problems. However, since the computing time for big sized problem can be long, we design three heuristic algorithms that based on the genetic algorithm. And then, some computational experiments are given to verify the performance of the algorithms.